1. Field of the Invention
The present invention relates to an optical module comprising an amplification optical fiber and a propagation optical fiber that are spliced to each other.
2. Related Background of the Invention
Recent years have witnessed growing interest in processing technologies that use laser light, and therefore the need for high-output laser light sources is ever greater in a wide variety of fields such as machinery manufacture, medicine and the like. Laser light sources that have been the focus of particular attention include fiber laser light sources, which use an amplification optical fiber, doped with rare earth elements such as Yb, Er, Tm and the like, as an amplification medium. In such fiber laser light sources, high-output laser light can be created within an amplification optical fiber by supplying pumping light to the amplification optical fiber, which is disposed inside a resonator structure. Fiber laser light sources are advantageous in that laser light is confined within the fiber. Therefore, such sources are easy to handle and have good thermal-radiation properties, and hence do not require large cooling equipment.
As an example of a technology in which such an amplification optical fiber is fusion-spliced to other optical fibers, Japanese Patent Application Laid-open No. 2008-187100 (Document 1) discloses the feature of providing a heat-transport portion, and a layer of a residual-light transmitting substance around a protective coating, with a view to removing pumping light in an optical fiber disposed after an amplification optical fiber. Meanwhile, Japanese Patent Application Laid-open No. 2008-268747 (Document 2) discloses the feature of causing pumping light to leak (removing pumping light) by providing a leak-light guide member in a fiber fused portion, and the feature of transporting heat by fixing the leak-light guide member to a heat-transport member by way of a resin member. These examples underscore the problem of how to treat pumping light after fusion splicing.
The resonator-type fiber laser light source shown in FIG. 1, for example, is configured so as to prevent pumping light from leaving the resonator, i.e. so as to prevent pumping light from propagating forward from the fiber splicing portion.